1. Field of the Invention
The present invention relates to absorbent elastomeric wound dressings which provide rapid absorption, good wicking, and high liquid retention. Background Information
A wound dressing having high sorbency and retention, high conformability, low density, and good wicking, and which is non-linting and economical has long been desired. Gauzes are today the most common wound dressing, but gauzes are expensive to make and exhibit some linting which is undesirable. Many attempts have been made to find a substitute for gauzes, but until now, no fully satisfactory substitute has been found.
One effort in absorbent products has involved incorporating absorbent additives in a fibrous web. Dressings capable of rapid uptake of wound exudate and subsequent retention of those fluids typically rely on absorptive media having low solidity or high void volume. Unfortunately, high void volume webs typically have low strength and hence poor integrity, a combination which generally results in the dressing tearing apart and leaving residues in the wound site when the dressing is removed. Additionally, when these dressings tear or are compressed during removal, they release fluids which have been absorbed, thereby soiling or contaminating patient bedding or clothing.
U.S. Pat. No 3,670,731 (Harmon) discloses the addition of hydrocolloidal particles to a fibrous mass, such as wood pulp, by cascading the particles into the fibrous mass. However, mechanical action causes the particles to dust out.
U.S. Pat. No. 4,366,814 (Riedel) discloses an elastic bandage material for medical tapes and dressing which has at least 50 percent by weight of an extensible porous fabric capable of elongation of at least 30 percent in one direction without tearing and at least 15 percent by weight of an elastomer uniformly impregnated in the fabric and substantially contained on or within the fibers of the fabric without filling the spaces between fibers. The fabric may be of a wide range of synthetic or natural fibers, used singly or in blends. The preferred elastomers include block copolymers, polyurethanes, acrylics, acrylic-olefinic copolymers, and other natural and synthetic rubbers.
U.S. Pat. No. 4,414,970 (Berry) discloses a moisture vapor transmitting elastic bandage which has an inner layer of fabric and an outer layer of fabric bonded to a central layer which is an elastomeric film. The film can be continuous, macroporous or microporous, but is preferably continuous to provide a bacterial barrier. Suitable films which may be obtained in continuous form and which transmit moisture vapor can be made from polyurethane, for example, a thermoplastic polyurethane.
U.S. Pat. No. 4,565,736 (Stein et al.) discloses a surgical compress which is made of an absorptive layer and a wound covering layer, the covering layer spun or otherwise made of nonwoven hydrophobic, hydrolysis-resistant, aliphatic polyurethane fibers, the covering layer preferably being autogenously bonded to the absorption layer by direct formation of tacky cover layer fibers on the absorption layer.
U.S. Pat. No. 4,715,857 (Juhasz et al.) disclose wound dressings which comprise, in order, a first layer of a permeable material, a layer of a semi-permeable, adhesive material, a charcoal cloth or felt, and a second layer of a permeable material, in which the three layers a substantially co-extensive and surround the charcoal cloth or felt, whereby the first layer of permeable material is bound to the cloth or felt and, around the cloth or felt, to the second layer of permeable material. The layers of permeable material are in the form of a fabric or film and may be of different or, preferably, the same material, examples of suitable materials being natural or synthetic rubber, nylon, polyester, polyurethane and rayon acetate, and other suitable synthetic polymers. The semi-permeable adhesive materials are preferably double-sided transfer tapes.
British Patent Specification No. 1,575,830 (Johnson & Johnson) discloses a flexible and conformable disposable absorbent dressing which comprises a layer of absorbent material, and a thin, flexible, elastic and easily stretchable thermoplastic backing film retained in superimposed relationship with the absorbent layer, the backing film possessing an elastic recovery from 50 percent stretch of at least 75 percent, a rubber modulus of not above 2000 pounds per square inch and a Gurley stiffness at a thickness of 1 mil of not above one. The film is preferably formed from A-B-A block copolymers which consist of A end blocks derived from styrene and B blocks derived from conjugated dienes.
U.S. Pat. No. 4,650,479 (Insley) discloses a sorbent sheet product comprising a coherent fibrous web that includes entangled blown polymeric fibers and high sorbency, liquid sorbent fibers intermingled with the blown polymeric fibers. The blown polymeric fibers may be formed from a wide variety of fiber-forming materials. Representative polymers for forming melt-blown fibers include polypropylene, polyethylene, polyethylene terephthalate, and polyamides.
European Patent Publication No. 0,156,649 (Insley et al.) discloses sorbent sheet products comprising a coherent fibrous web that includes entangled blown fibers and liquid transport fibers intermingled with the blown fibers and an array of solid high sorbency liquid-sorbent polymeric particles uniformly dispersed and physically held within the web. The particles swell upon sorption of liquid, and the transport fibers cause increased and more rapid sorption of liquid by conducting the liquid from external portions of the web to internal portions of the web.
U.S. Pat. No. 4,692,371 (Morman et al.) discloses elastomeric nonwoven webs of elastomeric meltblown fibers, elastomeric films or elastomeric molded materials attained by forming styrenic-(ethylenebutylene)-styrenic block copolymers at elevated temperatures of at least about 90.degree. C. In the case of elastomeric nonwoven webs of elastomeric fibers, other fibers, such as pulp or cellulosic fibers or nonfibrous material such as particulates, may be combined with the elastomeric fibers by known methods.
U.S. Pat. No. 4,692,368 (Taylor et al.) discloses a laminate which is elastic in at least one direction and includes an elastic sheet having at least one nonelastic, nonwoven web joined thereto at least at two areas. The nonelastic web is gathered between the two areas. The elastic sheet is formed from an aromatic polyetherurethane, preferably in the form of melt blown fibers The nonelastic nonwoven web includes spunlaced hydraulically entangled polyester fibers. The nonelastic nonwoven web may also include rayon or wood pulp fibers.
U.S. Pat. No. 4,118,531 (Hauser) discloses a web of blended microfibers and crimped bulking fibers. The web is a lofty resilient web which has high thermal resistance per unit of thickness and moderate weight, as well as other properties which give the web a distinctive utility as thermal insulation.